THERMAL ICING CONDITIONS DETECTOR

• US 20090003408A1
• Filed: 07/17/2008
• Published: 01/01/2009
• Est. Priority Date: 11/19/2002
• Status: Active Grant

• Current Assignee: Rosemount Aerospace, Inc. (Rtx Corporation)
• Original Assignee: Rosemount Aerospace, Inc. (Rtx Corporation)
• Inventors: Severson, John A.
• Granted Patent: US 7,674,036 B2
• Time in Patent Office: Days
• US Class Current: 374/16
• CPC Class Codes: B64D 15/20 Means for detecting icing or initiating de-icing
• CPC Class Codes: G01K 13/028 for use in total air temperature [TAT] probes
• CPC Class Codes: G08B 19/02 Alarm responsive to formation or anticipated formation of ice

Abstract

A sensor for detecting icing conditions in an airstream includes a flow housing mounted on an aircraft and in which one or more probes are mounted. At least one of the probes subjected to impingement of the airstream and liquid moisture droplets in such airstream. The heat removal, or cooling effect on the probe in the airstream carrying liquid droplets is determined. A temperature signal indicating the airstream temperature is combined with signals from the at least one probe for determining whether or not icing conditions are present.

Claims

1. A circuit indicating icing conditions, comprising:

an indicator of actual power consumed that is couplable to a heated probe in a portion of an airflow that is subject to liquid moisture content, the portion of the airflow including the liquid moisture content;

a pitot pressure sensor sensing the airflow;

a static pressure sensor sensing the airflow;

a total air temperature sensor sensing the airflow; and

a computer calculating, as a function of the sensed static and pitot pressures and total air temperature, an amount of power that would be consumed by the heated sensor in a dry airflow, and the computer also coupled to the indicator to receive an indication of the amount of power that is actually consumed by the heated probe in the portion of airflow subject to liquid moisture, the computer providing an output indicating the presence of liquid moisture in the airflow at ambient temperatures that are above freezing.

2. The circuit of claim 1 wherein the computer provides power that is couplable through the power consumed indicator to the heated probe.

3. The circuit of claim 2 wherein the computer maintains the power consumed at a desired level.

4. The circuit of claim 1 wherein the computer comprises a mass flow rate as a function of the total air temperature and the pitot and static pressure inputs.

5. The circuit of claim 4 wherein the computer determines an amount of power that would be consumed at the computed mass flow rate.

6. A method of indicating the presence of liquid moisture in an airflow, comprising:

sensing mass flow rate data of an airflow;

sensing a first heat removal from a first heated temperature sensor subject to heat removal by airflow from which liquid moisture has not been removed;

coupling the sensed mass flow rate data and the first sensed heat removal to a computer; and

computing in the computer, as a function of the mass flow rate data and the first sensed heat removal, the presence of liquid moisture in the airflow.

7. The method of claim 6 wherein the sensed mass flow rate data is obtained by sensing a second heat removal from a second heated temperature sensor subject to heat removal by airflow from which liquid moisture has been removed.

8. The method of claim 6 wherein the sensed mass flow rate data is obtained by sensing pitot and static pressures and total air temperature.

9. The method of claim 6 and further comprising:

generating an icing condition output indicating the presence of liquid moisture in the airflow at ambient temperatures that are above freezing.

10. The method of claim 6 and further comprising:

coupling the first heated temperature sensor to the computer through a bridge Circuit that comprises resistors.

11. The method of claim 10 and further comprising filtering signals from the bridge circuit due to snow and ice prior to coupling the bridge to the computer.

12. The method of claim 10 and further comprising:

coupling the bridge circuit to a voltage supply.